
/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>

#define NGX_HTTP_SSI_ERROR 1

#define NGX_HTTP_SSI_DATE_LEN 2048

#define NGX_HTTP_SSI_ADD_PREFIX 1
#define NGX_HTTP_SSI_ADD_ZERO   2


typedef struct
{
    ngx_flag_t enable;
    ngx_flag_t silent_errors;
    ngx_flag_t ignore_recycled_buffers;
    ngx_flag_t last_modified;

    ngx_hash_t types;

    size_t min_file_chunk;
    size_t value_len;

    ngx_array_t *types_keys;
} ngx_http_ssi_loc_conf_t;


typedef struct
{
    ngx_str_t  name;
    ngx_uint_t key;
    ngx_str_t  value;
} ngx_http_ssi_var_t;


typedef struct
{
    ngx_str_t    name;
    ngx_chain_t *bufs;
    ngx_uint_t   count;
} ngx_http_ssi_block_t;


typedef enum
{
    ssi_start_state = 0,
    ssi_tag_state,
    ssi_comment0_state,
    ssi_comment1_state,
    ssi_sharp_state,
    ssi_precommand_state,
    ssi_command_state,
    ssi_preparam_state,
    ssi_param_state,
    ssi_preequal_state,
    ssi_prevalue_state,
    ssi_double_quoted_value_state,
    ssi_quoted_value_state,
    ssi_quoted_symbol_state,
    ssi_postparam_state,
    ssi_comment_end0_state,
    ssi_comment_end1_state,
    ssi_error_state,
    ssi_error_end0_state,
    ssi_error_end1_state
} ngx_http_ssi_state_e;


static ngx_int_t  ngx_http_ssi_output(ngx_http_request_t *r,
                                      ngx_http_ssi_ctx_t *ctx);
static void       ngx_http_ssi_buffered(ngx_http_request_t *r,
                                        ngx_http_ssi_ctx_t *ctx);
static ngx_int_t  ngx_http_ssi_parse(ngx_http_request_t *r,
                                     ngx_http_ssi_ctx_t *ctx);
static ngx_str_t *ngx_http_ssi_get_variable(ngx_http_request_t *r,
                                            ngx_str_t *name, ngx_uint_t key);
static ngx_int_t  ngx_http_ssi_evaluate_string(ngx_http_request_t *r,
                                               ngx_http_ssi_ctx_t *ctx,
                                               ngx_str_t          *text,
                                               ngx_uint_t          flags);
static ngx_int_t  ngx_http_ssi_regex_match(ngx_http_request_t *r,
                                           ngx_str_t *pattern, ngx_str_t *str);

static ngx_int_t ngx_http_ssi_include(ngx_http_request_t *r,
                                      ngx_http_ssi_ctx_t *ctx,
                                      ngx_str_t         **params);
static ngx_int_t ngx_http_ssi_stub_output(ngx_http_request_t *r, void *data,
                                          ngx_int_t rc);
static ngx_int_t ngx_http_ssi_set_variable(ngx_http_request_t *r, void *data,
                                           ngx_int_t rc);
static ngx_int_t ngx_http_ssi_echo(ngx_http_request_t *r,
                                   ngx_http_ssi_ctx_t *ctx, ngx_str_t **params);
static ngx_int_t ngx_http_ssi_config(ngx_http_request_t *r,
                                     ngx_http_ssi_ctx_t *ctx,
                                     ngx_str_t         **params);
static ngx_int_t ngx_http_ssi_set(ngx_http_request_t *r,
                                  ngx_http_ssi_ctx_t *ctx, ngx_str_t **params);
static ngx_int_t ngx_http_ssi_if(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                                 ngx_str_t **params);
static ngx_int_t ngx_http_ssi_else(ngx_http_request_t *r,
                                   ngx_http_ssi_ctx_t *ctx, ngx_str_t **params);
static ngx_int_t ngx_http_ssi_endif(ngx_http_request_t *r,
                                    ngx_http_ssi_ctx_t *ctx,
                                    ngx_str_t         **params);
static ngx_int_t ngx_http_ssi_block(ngx_http_request_t *r,
                                    ngx_http_ssi_ctx_t *ctx,
                                    ngx_str_t         **params);
static ngx_int_t ngx_http_ssi_endblock(ngx_http_request_t *r,
                                       ngx_http_ssi_ctx_t *ctx,
                                       ngx_str_t         **params);

static ngx_int_t ngx_http_ssi_date_gmt_local_variable(
    ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t gmt);

static ngx_int_t ngx_http_ssi_preconfiguration(ngx_conf_t *cf);
static void     *ngx_http_ssi_create_main_conf(ngx_conf_t *cf);
static char     *ngx_http_ssi_init_main_conf(ngx_conf_t *cf, void *conf);
static void     *ngx_http_ssi_create_loc_conf(ngx_conf_t *cf);
static char     *ngx_http_ssi_merge_loc_conf(ngx_conf_t *cf, void *parent,
                                             void *child);
static ngx_int_t ngx_http_ssi_filter_init(ngx_conf_t *cf);


static ngx_command_t ngx_http_ssi_filter_commands[] = {

    {ngx_string("ssi"),
     NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF
         | NGX_HTTP_LIF_CONF | NGX_CONF_FLAG,
     ngx_conf_set_flag_slot, NGX_HTTP_LOC_CONF_OFFSET,
     offsetof(ngx_http_ssi_loc_conf_t, enable), NULL},

    {ngx_string("ssi_silent_errors"),
     NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_FLAG,
     ngx_conf_set_flag_slot, NGX_HTTP_LOC_CONF_OFFSET,
     offsetof(ngx_http_ssi_loc_conf_t, silent_errors), NULL},

    {ngx_string("ssi_ignore_recycled_buffers"),
     NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_FLAG,
     ngx_conf_set_flag_slot, NGX_HTTP_LOC_CONF_OFFSET,
     offsetof(ngx_http_ssi_loc_conf_t, ignore_recycled_buffers), NULL},

    {ngx_string("ssi_min_file_chunk"),
     NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF
         | NGX_CONF_TAKE1,
     ngx_conf_set_size_slot, NGX_HTTP_LOC_CONF_OFFSET,
     offsetof(ngx_http_ssi_loc_conf_t, min_file_chunk), NULL},

    {ngx_string("ssi_value_length"),
     NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF
         | NGX_CONF_TAKE1,
     ngx_conf_set_size_slot, NGX_HTTP_LOC_CONF_OFFSET,
     offsetof(ngx_http_ssi_loc_conf_t, value_len), NULL},

    {ngx_string("ssi_types"),
     NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF
         | NGX_CONF_1MORE,
     ngx_http_types_slot, NGX_HTTP_LOC_CONF_OFFSET,
     offsetof(ngx_http_ssi_loc_conf_t, types_keys),
     &ngx_http_html_default_types[0]},

    {ngx_string("ssi_last_modified"),
     NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_FLAG,
     ngx_conf_set_flag_slot, NGX_HTTP_LOC_CONF_OFFSET,
     offsetof(ngx_http_ssi_loc_conf_t, last_modified), NULL},

    ngx_null_command};


static ngx_http_module_t ngx_http_ssi_filter_module_ctx = {
    ngx_http_ssi_preconfiguration, /* preconfiguration */
    ngx_http_ssi_filter_init,      /* postconfiguration */

    ngx_http_ssi_create_main_conf, /* create main configuration */
    ngx_http_ssi_init_main_conf,   /* init main configuration */

    NULL, /* create server configuration */
    NULL, /* merge server configuration */

    ngx_http_ssi_create_loc_conf, /* create location configuration */
    ngx_http_ssi_merge_loc_conf   /* merge location configuration */
};


ngx_module_t ngx_http_ssi_filter_module = {
    NGX_MODULE_V1,
    &ngx_http_ssi_filter_module_ctx, /* module context */
    ngx_http_ssi_filter_commands,    /* module directives */
    NGX_HTTP_MODULE,                 /* module type */
    NULL,                            /* init master */
    NULL,                            /* init module */
    NULL,                            /* init process */
    NULL,                            /* init thread */
    NULL,                            /* exit thread */
    NULL,                            /* exit process */
    NULL,                            /* exit master */
    NGX_MODULE_V1_PADDING};


static ngx_http_output_header_filter_pt ngx_http_next_header_filter;
static ngx_http_output_body_filter_pt   ngx_http_next_body_filter;


static u_char ngx_http_ssi_string[] = "<!--";

static ngx_str_t ngx_http_ssi_none    = ngx_string("(none)");
static ngx_str_t ngx_http_ssi_timefmt = ngx_string("%A, %d-%b-%Y %H:%M:%S %Z");
static ngx_str_t ngx_http_ssi_null_string = ngx_null_string;


#define NGX_HTTP_SSI_INCLUDE_VIRTUAL 0
#define NGX_HTTP_SSI_INCLUDE_FILE    1
#define NGX_HTTP_SSI_INCLUDE_WAIT    2
#define NGX_HTTP_SSI_INCLUDE_SET     3
#define NGX_HTTP_SSI_INCLUDE_STUB    4

#define NGX_HTTP_SSI_ECHO_VAR      0
#define NGX_HTTP_SSI_ECHO_DEFAULT  1
#define NGX_HTTP_SSI_ECHO_ENCODING 2

#define NGX_HTTP_SSI_CONFIG_ERRMSG  0
#define NGX_HTTP_SSI_CONFIG_TIMEFMT 1

#define NGX_HTTP_SSI_SET_VAR   0
#define NGX_HTTP_SSI_SET_VALUE 1

#define NGX_HTTP_SSI_IF_EXPR 0

#define NGX_HTTP_SSI_BLOCK_NAME 0


static ngx_http_ssi_param_t ngx_http_ssi_include_params[] = {
    {ngx_string("virtual"), NGX_HTTP_SSI_INCLUDE_VIRTUAL, 0, 0},
    {ngx_string("file"), NGX_HTTP_SSI_INCLUDE_FILE, 0, 0},
    {ngx_string("wait"), NGX_HTTP_SSI_INCLUDE_WAIT, 0, 0},
    {ngx_string("set"), NGX_HTTP_SSI_INCLUDE_SET, 0, 0},
    {ngx_string("stub"), NGX_HTTP_SSI_INCLUDE_STUB, 0, 0},
    {ngx_null_string, 0, 0, 0}};


static ngx_http_ssi_param_t ngx_http_ssi_echo_params[] = {
    {ngx_string("var"), NGX_HTTP_SSI_ECHO_VAR, 1, 0},
    {ngx_string("default"), NGX_HTTP_SSI_ECHO_DEFAULT, 0, 0},
    {ngx_string("encoding"), NGX_HTTP_SSI_ECHO_ENCODING, 0, 0},
    {ngx_null_string, 0, 0, 0}};


static ngx_http_ssi_param_t ngx_http_ssi_config_params[] = {
    {ngx_string("errmsg"), NGX_HTTP_SSI_CONFIG_ERRMSG, 0, 0},
    {ngx_string("timefmt"), NGX_HTTP_SSI_CONFIG_TIMEFMT, 0, 0},
    {ngx_null_string, 0, 0, 0}};


static ngx_http_ssi_param_t ngx_http_ssi_set_params[] = {
    {ngx_string("var"), NGX_HTTP_SSI_SET_VAR, 1, 0},
    {ngx_string("value"), NGX_HTTP_SSI_SET_VALUE, 1, 0},
    {ngx_null_string, 0, 0, 0}};


static ngx_http_ssi_param_t ngx_http_ssi_if_params[] = {
    {ngx_string("expr"), NGX_HTTP_SSI_IF_EXPR, 1, 0},
    {ngx_null_string, 0, 0, 0}};


static ngx_http_ssi_param_t ngx_http_ssi_block_params[] = {
    {ngx_string("name"), NGX_HTTP_SSI_BLOCK_NAME, 1, 0},
    {ngx_null_string, 0, 0, 0}};


static ngx_http_ssi_param_t ngx_http_ssi_no_params[] = {
    {ngx_null_string, 0, 0, 0}};


static ngx_http_ssi_command_t ngx_http_ssi_commands[] = {
    {ngx_string("include"), ngx_http_ssi_include, ngx_http_ssi_include_params,
     0, 0, 1},
    {ngx_string("echo"), ngx_http_ssi_echo, ngx_http_ssi_echo_params, 0, 0, 0},
    {ngx_string("config"), ngx_http_ssi_config, ngx_http_ssi_config_params, 0,
     0, 0},
    {ngx_string("set"), ngx_http_ssi_set, ngx_http_ssi_set_params, 0, 0, 0},

    {ngx_string("if"), ngx_http_ssi_if, ngx_http_ssi_if_params, 0, 0, 0},
    {ngx_string("elif"), ngx_http_ssi_if, ngx_http_ssi_if_params,
     NGX_HTTP_SSI_COND_IF, 0, 0},
    {ngx_string("else"), ngx_http_ssi_else, ngx_http_ssi_no_params,
     NGX_HTTP_SSI_COND_IF, 0, 0},
    {ngx_string("endif"), ngx_http_ssi_endif, ngx_http_ssi_no_params,
     NGX_HTTP_SSI_COND_ELSE, 0, 0},

    {ngx_string("block"), ngx_http_ssi_block, ngx_http_ssi_block_params, 0, 0,
     0},
    {ngx_string("endblock"), ngx_http_ssi_endblock, ngx_http_ssi_no_params, 0,
     1, 0},

    {ngx_null_string, NULL, NULL, 0, 0, 0}};


static ngx_http_variable_t ngx_http_ssi_vars[] = {

    {ngx_string("date_local"), NULL, ngx_http_ssi_date_gmt_local_variable, 0,
     NGX_HTTP_VAR_NOCACHEABLE, 0},

    {ngx_string("date_gmt"), NULL, ngx_http_ssi_date_gmt_local_variable, 1,
     NGX_HTTP_VAR_NOCACHEABLE, 0},

    ngx_http_null_variable};


static ngx_int_t
ngx_http_ssi_header_filter(ngx_http_request_t *r)
{
    ngx_http_ssi_ctx_t      *ctx;
    ngx_http_ssi_loc_conf_t *slcf;

    slcf = ngx_http_get_module_loc_conf(r, ngx_http_ssi_filter_module);

    if (!slcf->enable || r->headers_out.content_length_n == 0
        || ngx_http_test_content_type(r, &slcf->types) == NULL)
    {
        return ngx_http_next_header_filter(r);
    }

    ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_ssi_ctx_t));
    if (ctx == NULL)
    {
        return NGX_ERROR;
    }

    ngx_http_set_ctx(r, ctx, ngx_http_ssi_filter_module);


    ctx->value_len = slcf->value_len;
    ctx->last_out  = &ctx->out;

    ctx->encoding = NGX_HTTP_SSI_ENTITY_ENCODING;
    ctx->output   = 1;

    ctx->params.elts   = ctx->params_array;
    ctx->params.size   = sizeof(ngx_table_elt_t);
    ctx->params.nalloc = NGX_HTTP_SSI_PARAMS_N;
    ctx->params.pool   = r->pool;

    ctx->timefmt = ngx_http_ssi_timefmt;
    ngx_str_set(&ctx->errmsg,
                "[an error occurred while processing the directive]");

    r->filter_need_in_memory = 1;

    if (r == r->main)
    {
        ngx_http_clear_content_length(r);
        ngx_http_clear_accept_ranges(r);

        r->preserve_body = 1;

        if (!slcf->last_modified)
        {
            ngx_http_clear_last_modified(r);
            ngx_http_clear_etag(r);
        }
        else
        {
            ngx_http_weak_etag(r);
        }
    }

    return ngx_http_next_header_filter(r);
}


static ngx_int_t
ngx_http_ssi_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    size_t                    len;
    ngx_int_t                 rc;
    ngx_buf_t                *b;
    ngx_uint_t                i, index;
    ngx_chain_t              *cl, **ll;
    ngx_table_elt_t          *param;
    ngx_http_ssi_ctx_t       *ctx, *mctx;
    ngx_http_ssi_block_t     *bl;
    ngx_http_ssi_param_t     *prm;
    ngx_http_ssi_command_t   *cmd;
    ngx_http_ssi_loc_conf_t  *slcf;
    ngx_http_ssi_main_conf_t *smcf;
    ngx_str_t                *params[NGX_HTTP_SSI_MAX_PARAMS + 1];

    ctx = ngx_http_get_module_ctx(r, ngx_http_ssi_filter_module);

    if (ctx == NULL
        || (in == NULL && ctx->buf == NULL && ctx->in == NULL
            && ctx->busy == NULL))
    {
        return ngx_http_next_body_filter(r, in);
    }

    /* add the incoming chain to the chain ctx->in */

    if (in)
    {
        if (ngx_chain_add_copy(r->pool, &ctx->in, in) != NGX_OK)
        {
            return NGX_ERROR;
        }
    }

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http ssi filter \"%V?%V\"", &r->uri, &r->args);

    if (ctx->wait)
    {
        if (r != r->connection->data)
        {
            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "http ssi filter wait \"%V?%V\" non-active",
                           &ctx->wait->uri, &ctx->wait->args);

            return NGX_AGAIN;
        }

        if (ctx->wait->done)
        {
            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "http ssi filter wait \"%V?%V\" done",
                           &ctx->wait->uri, &ctx->wait->args);

            ctx->wait = NULL;
        }
        else
        {
            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "http ssi filter wait \"%V?%V\"", &ctx->wait->uri,
                           &ctx->wait->args);

            return ngx_http_next_body_filter(r, NULL);
        }
    }

    slcf = ngx_http_get_module_loc_conf(r, ngx_http_ssi_filter_module);

    while (ctx->in || ctx->buf)
    {
        if (ctx->buf == NULL)
        {
            ctx->buf = ctx->in->buf;
            ctx->in  = ctx->in->next;
            ctx->pos = ctx->buf->pos;
        }

        if (ctx->state == ssi_start_state)
        {
            ctx->copy_start = ctx->pos;
            ctx->copy_end   = ctx->pos;
        }

        b = NULL;

        while (ctx->pos < ctx->buf->last)
        {
            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "saved: %uz state: %ui", ctx->saved, ctx->state);

            rc = ngx_http_ssi_parse(r, ctx);

            ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "parse: %i, looked: %uz %p-%p", rc, ctx->looked,
                           ctx->copy_start, ctx->copy_end);

            if (rc == NGX_ERROR)
            {
                return rc;
            }

            if (ctx->copy_start != ctx->copy_end)
            {
                if (ctx->output)
                {
                    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                                   "saved: %uz", ctx->saved);

                    if (ctx->saved)
                    {
                        if (ctx->free)
                        {
                            cl        = ctx->free;
                            ctx->free = ctx->free->next;
                            b         = cl->buf;
                            ngx_memzero(b, sizeof(ngx_buf_t));
                        }
                        else
                        {
                            b = ngx_calloc_buf(r->pool);
                            if (b == NULL)
                            {
                                return NGX_ERROR;
                            }

                            cl = ngx_alloc_chain_link(r->pool);
                            if (cl == NULL)
                            {
                                return NGX_ERROR;
                            }

                            cl->buf = b;
                        }

                        b->memory = 1;
                        b->pos    = ngx_http_ssi_string;
                        b->last   = ngx_http_ssi_string + ctx->saved;

                        *ctx->last_out = cl;
                        ctx->last_out  = &cl->next;

                        ctx->saved = 0;
                    }

                    if (ctx->free)
                    {
                        cl        = ctx->free;
                        ctx->free = ctx->free->next;
                        b         = cl->buf;
                    }
                    else
                    {
                        b = ngx_alloc_buf(r->pool);
                        if (b == NULL)
                        {
                            return NGX_ERROR;
                        }

                        cl = ngx_alloc_chain_link(r->pool);
                        if (cl == NULL)
                        {
                            return NGX_ERROR;
                        }

                        cl->buf = b;
                    }

                    ngx_memcpy(b, ctx->buf, sizeof(ngx_buf_t));

                    b->pos      = ctx->copy_start;
                    b->last     = ctx->copy_end;
                    b->shadow   = NULL;
                    b->last_buf = 0;
                    b->recycled = 0;

                    if (b->in_file)
                    {
                        if (slcf->min_file_chunk < (size_t)(b->last - b->pos))
                        {
                            b->file_last =
                                b->file_pos + (b->last - ctx->buf->pos);
                            b->file_pos += b->pos - ctx->buf->pos;
                        }
                        else
                        {
                            b->in_file = 0;
                        }
                    }

                    cl->next       = NULL;
                    *ctx->last_out = cl;
                    ctx->last_out  = &cl->next;
                }
                else
                {
                    if (ctx->block
                        && ctx->saved + (ctx->copy_end - ctx->copy_start))
                    {
                        b = ngx_create_temp_buf(
                            r->pool,
                            ctx->saved + (ctx->copy_end - ctx->copy_start));

                        if (b == NULL)
                        {
                            return NGX_ERROR;
                        }

                        if (ctx->saved)
                        {
                            b->last = ngx_cpymem(b->pos, ngx_http_ssi_string,
                                                 ctx->saved);
                        }

                        b->last = ngx_cpymem(b->last, ctx->copy_start,
                                             ctx->copy_end - ctx->copy_start);

                        cl = ngx_alloc_chain_link(r->pool);
                        if (cl == NULL)
                        {
                            return NGX_ERROR;
                        }

                        cl->buf  = b;
                        cl->next = NULL;

                        b = NULL;

                        mctx = ngx_http_get_module_ctx(
                            r->main, ngx_http_ssi_filter_module);
                        bl = mctx->blocks->elts;
                        for (ll = &bl[mctx->blocks->nelts - 1].bufs; *ll;
                             ll = &(*ll)->next)
                        {
                            /* void */
                        }

                        *ll = cl;
                    }

                    ctx->saved = 0;
                }
            }

            if (ctx->state == ssi_start_state)
            {
                ctx->copy_start = ctx->pos;
                ctx->copy_end   = ctx->pos;
            }
            else
            {
                ctx->copy_start = NULL;
                ctx->copy_end   = NULL;
            }

            if (rc == NGX_AGAIN)
            {
                continue;
            }


            b = NULL;

            if (rc == NGX_OK)
            {
                smcf = ngx_http_get_module_main_conf(
                    r, ngx_http_ssi_filter_module);

                cmd = ngx_hash_find(&smcf->hash, ctx->key, ctx->command.data,
                                    ctx->command.len);

                if (cmd == NULL)
                {
                    if (ctx->output)
                    {
                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                      "invalid SSI command: \"%V\"",
                                      &ctx->command);
                        goto ssi_error;
                    }

                    continue;
                }

                if (!ctx->output && !cmd->block)
                {
                    if (ctx->block)
                    {
                        /* reconstruct the SSI command text */

                        len = 5 + ctx->command.len + 4;

                        param = ctx->params.elts;
                        for (i = 0; i < ctx->params.nelts; i++)
                        {
                            len += 1 + param[i].key.len + 2 + param[i].value.len
                                   + 1;
                        }

                        b = ngx_create_temp_buf(r->pool, len);

                        if (b == NULL)
                        {
                            return NGX_ERROR;
                        }

                        cl = ngx_alloc_chain_link(r->pool);
                        if (cl == NULL)
                        {
                            return NGX_ERROR;
                        }

                        cl->buf  = b;
                        cl->next = NULL;

                        *b->last++ = '<';
                        *b->last++ = '!';
                        *b->last++ = '-';
                        *b->last++ = '-';
                        *b->last++ = '#';

                        b->last = ngx_cpymem(b->last, ctx->command.data,
                                             ctx->command.len);

                        for (i = 0; i < ctx->params.nelts; i++)
                        {
                            *b->last++ = ' ';
                            b->last    = ngx_cpymem(b->last, param[i].key.data,
                                                    param[i].key.len);
                            *b->last++ = '=';
                            *b->last++ = '"';
                            b->last = ngx_cpymem(b->last, param[i].value.data,
                                                 param[i].value.len);
                            *b->last++ = '"';
                        }

                        *b->last++ = ' ';
                        *b->last++ = '-';
                        *b->last++ = '-';
                        *b->last++ = '>';

                        mctx = ngx_http_get_module_ctx(
                            r->main, ngx_http_ssi_filter_module);
                        bl = mctx->blocks->elts;
                        for (ll = &bl[mctx->blocks->nelts - 1].bufs; *ll;
                             ll = &(*ll)->next)
                        {
                            /* void */
                        }

                        *ll = cl;

                        b = NULL;

                        continue;
                    }

                    if (cmd->conditional == 0)
                    {
                        continue;
                    }
                }

                if (cmd->conditional
                    && (ctx->conditional == 0
                        || ctx->conditional > cmd->conditional))
                {
                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                  "invalid context of SSI command: \"%V\"",
                                  &ctx->command);
                    goto ssi_error;
                }

                if (ctx->params.nelts > NGX_HTTP_SSI_MAX_PARAMS)
                {
                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                  "too many SSI command parameters: \"%V\"",
                                  &ctx->command);
                    goto ssi_error;
                }

                ngx_memzero(params, (NGX_HTTP_SSI_MAX_PARAMS + 1)
                                        * sizeof(ngx_str_t *));

                param = ctx->params.elts;

                for (i = 0; i < ctx->params.nelts; i++)
                {
                    for (prm = cmd->params; prm->name.len; prm++)
                    {
                        if (param[i].key.len != prm->name.len
                            || ngx_strncmp(param[i].key.data, prm->name.data,
                                           prm->name.len)
                                   != 0)
                        {
                            continue;
                        }

                        if (!prm->multiple)
                        {
                            if (params[prm->index])
                            {
                                ngx_log_error(NGX_LOG_ERR, r->connection->log,
                                              0,
                                              "duplicate \"%V\" parameter "
                                              "in \"%V\" SSI command",
                                              &param[i].key, &ctx->command);

                                goto ssi_error;
                            }

                            params[prm->index] = &param[i].value;

                            break;
                        }

                        for (index = prm->index; params[index]; index++)
                        {
                            /* void */
                        }

                        params[index] = &param[i].value;

                        break;
                    }

                    if (prm->name.len == 0)
                    {
                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                      "invalid parameter name: \"%V\" "
                                      "in \"%V\" SSI command",
                                      &param[i].key, &ctx->command);

                        goto ssi_error;
                    }
                }

                for (prm = cmd->params; prm->name.len; prm++)
                {
                    if (prm->mandatory && params[prm->index] == 0)
                    {
                        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                      "mandatory \"%V\" parameter is absent "
                                      "in \"%V\" SSI command",
                                      &prm->name, &ctx->command);

                        goto ssi_error;
                    }
                }

                if (cmd->flush && ctx->out)
                {
                    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                                   "ssi flush");

                    if (ngx_http_ssi_output(r, ctx) == NGX_ERROR)
                    {
                        return NGX_ERROR;
                    }
                }

                rc = cmd->handler(r, ctx, params);

                if (rc == NGX_OK)
                {
                    continue;
                }

                if (rc == NGX_DONE || rc == NGX_AGAIN || rc == NGX_ERROR)
                {
                    ngx_http_ssi_buffered(r, ctx);
                    return rc;
                }
            }


            /* rc == NGX_HTTP_SSI_ERROR */

        ssi_error:

            if (slcf->silent_errors)
            {
                continue;
            }

            if (ctx->free)
            {
                cl        = ctx->free;
                ctx->free = ctx->free->next;
                b         = cl->buf;
                ngx_memzero(b, sizeof(ngx_buf_t));
            }
            else
            {
                b = ngx_calloc_buf(r->pool);
                if (b == NULL)
                {
                    return NGX_ERROR;
                }

                cl = ngx_alloc_chain_link(r->pool);
                if (cl == NULL)
                {
                    return NGX_ERROR;
                }

                cl->buf = b;
            }

            b->memory = 1;
            b->pos    = ctx->errmsg.data;
            b->last   = ctx->errmsg.data + ctx->errmsg.len;

            cl->next       = NULL;
            *ctx->last_out = cl;
            ctx->last_out  = &cl->next;

            continue;
        }

        if (ctx->buf->last_buf || ngx_buf_in_memory(ctx->buf))
        {
            if (b == NULL)
            {
                if (ctx->free)
                {
                    cl        = ctx->free;
                    ctx->free = ctx->free->next;
                    b         = cl->buf;
                    ngx_memzero(b, sizeof(ngx_buf_t));
                }
                else
                {
                    b = ngx_calloc_buf(r->pool);
                    if (b == NULL)
                    {
                        return NGX_ERROR;
                    }

                    cl = ngx_alloc_chain_link(r->pool);
                    if (cl == NULL)
                    {
                        return NGX_ERROR;
                    }

                    cl->buf = b;
                }

                b->sync = 1;

                cl->next       = NULL;
                *ctx->last_out = cl;
                ctx->last_out  = &cl->next;
            }

            b->last_buf = ctx->buf->last_buf;
            b->shadow   = ctx->buf;

            if (slcf->ignore_recycled_buffers == 0)
            {
                b->recycled = ctx->buf->recycled;
            }
        }

        ctx->buf = NULL;

        ctx->saved = ctx->looked;
    }

    if (ctx->out == NULL && ctx->busy == NULL)
    {
        return NGX_OK;
    }

    return ngx_http_ssi_output(r, ctx);
}


static ngx_int_t
ngx_http_ssi_output(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx)
{
    ngx_int_t    rc;
    ngx_buf_t   *b;
    ngx_chain_t *cl;

#if 1
    b = NULL;
    for (cl = ctx->out; cl; cl = cl->next)
    {
        ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "ssi out: %p %p", cl->buf, cl->buf->pos);
        if (cl->buf == b)
        {
            ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                          "the same buf was used in ssi");
            ngx_debug_point();
            return NGX_ERROR;
        }
        b = cl->buf;
    }
#endif

    rc = ngx_http_next_body_filter(r, ctx->out);

    if (ctx->busy == NULL)
    {
        ctx->busy = ctx->out;
    }
    else
    {
        for (cl = ctx->busy; cl->next; cl = cl->next)
        { /* void */
        }
        cl->next = ctx->out;
    }

    ctx->out      = NULL;
    ctx->last_out = &ctx->out;

    while (ctx->busy)
    {
        cl = ctx->busy;
        b  = cl->buf;

        if (ngx_buf_size(b) != 0)
        {
            break;
        }

        if (b->shadow)
        {
            b->shadow->pos = b->shadow->last;
        }

        ctx->busy = cl->next;

        if (ngx_buf_in_memory(b) || b->in_file)
        {
            /* add data bufs only to the free buf chain */

            cl->next  = ctx->free;
            ctx->free = cl;
        }
    }

    ngx_http_ssi_buffered(r, ctx);

    return rc;
}


static void
ngx_http_ssi_buffered(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx)
{
    if (ctx->in || ctx->buf)
    {
        r->buffered |= NGX_HTTP_SSI_BUFFERED;
    }
    else
    {
        r->buffered &= ~NGX_HTTP_SSI_BUFFERED;
    }
}


static ngx_int_t
ngx_http_ssi_parse(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx)
{
    u_char              *p, *value, *last, *copy_end, ch;
    size_t               looked;
    ngx_http_ssi_state_e state;

    state    = ctx->state;
    looked   = ctx->looked;
    last     = ctx->buf->last;
    copy_end = ctx->copy_end;

    for (p = ctx->pos; p < last; p++)
    {
        ch = *p;

        if (state == ssi_start_state)
        {
            /* the tight loop */

            for (;;)
            {
                if (ch == '<')
                {
                    copy_end = p;
                    looked   = 1;
                    state    = ssi_tag_state;

                    goto tag_started;
                }

                if (++p == last)
                {
                    break;
                }

                ch = *p;
            }

            ctx->state    = state;
            ctx->pos      = p;
            ctx->looked   = looked;
            ctx->copy_end = p;

            if (ctx->copy_start == NULL)
            {
                ctx->copy_start = ctx->buf->pos;
            }

            return NGX_AGAIN;

        tag_started:

            continue;
        }

        switch (state)
        {
        case ssi_start_state:
            /* not reached */
            break;

        case ssi_tag_state:
            switch (ch)
            {
            case '!':
                looked = 2;
                state  = ssi_comment0_state;
                break;

            case '<': copy_end = p; break;

            default:
                copy_end = p;
                looked   = 0;
                state    = ssi_start_state;
                break;
            }

            break;

        case ssi_comment0_state:
            switch (ch)
            {
            case '-':
                looked = 3;
                state  = ssi_comment1_state;
                break;

            case '<':
                copy_end = p;
                looked   = 1;
                state    = ssi_tag_state;
                break;

            default:
                copy_end = p;
                looked   = 0;
                state    = ssi_start_state;
                break;
            }

            break;

        case ssi_comment1_state:
            switch (ch)
            {
            case '-':
                looked = 4;
                state  = ssi_sharp_state;
                break;

            case '<':
                copy_end = p;
                looked   = 1;
                state    = ssi_tag_state;
                break;

            default:
                copy_end = p;
                looked   = 0;
                state    = ssi_start_state;
                break;
            }

            break;

        case ssi_sharp_state:
            switch (ch)
            {
            case '#':
                if (p - ctx->pos < 4)
                {
                    ctx->saved = 0;
                }
                looked = 0;
                state  = ssi_precommand_state;
                break;

            case '<':
                copy_end = p;
                looked   = 1;
                state    = ssi_tag_state;
                break;

            default:
                copy_end = p;
                looked   = 0;
                state    = ssi_start_state;
                break;
            }

            break;

        case ssi_precommand_state:
            switch (ch)
            {
            case ' ':
            case CR:
            case LF:
            case '\t': break;

            default:
                ctx->command.len = 1;
                ctx->command.data =
                    ngx_pnalloc(r->pool, NGX_HTTP_SSI_COMMAND_LEN);
                if (ctx->command.data == NULL)
                {
                    return NGX_ERROR;
                }

                ctx->command.data[0] = ch;

                ctx->key = 0;
                ctx->key = ngx_hash(ctx->key, ch);

                ctx->params.nelts = 0;

                state = ssi_command_state;
                break;
            }

            break;

        case ssi_command_state:
            switch (ch)
            {
            case ' ':
            case CR:
            case LF:
            case '\t': state = ssi_preparam_state; break;

            case '-': state = ssi_comment_end0_state; break;

            default:
                if (ctx->command.len == NGX_HTTP_SSI_COMMAND_LEN)
                {
                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                  "the \"%V%c...\" SSI command is too long",
                                  &ctx->command, ch);

                    state = ssi_error_state;
                    break;
                }

                ctx->command.data[ctx->command.len++] = ch;
                ctx->key                              = ngx_hash(ctx->key, ch);
            }

            break;

        case ssi_preparam_state:
            switch (ch)
            {
            case ' ':
            case CR:
            case LF:
            case '\t': break;

            case '-': state = ssi_comment_end0_state; break;

            default:
                ctx->param = ngx_array_push(&ctx->params);
                if (ctx->param == NULL)
                {
                    return NGX_ERROR;
                }

                ctx->param->key.len = 1;
                ctx->param->key.data =
                    ngx_pnalloc(r->pool, NGX_HTTP_SSI_PARAM_LEN);
                if (ctx->param->key.data == NULL)
                {
                    return NGX_ERROR;
                }

                ctx->param->key.data[0] = ch;

                ctx->param->value.len = 0;

                if (ctx->value_buf == NULL)
                {
                    ctx->param->value.data =
                        ngx_pnalloc(r->pool, ctx->value_len + 1);
                    if (ctx->param->value.data == NULL)
                    {
                        return NGX_ERROR;
                    }
                }
                else
                {
                    ctx->param->value.data = ctx->value_buf;
                }

                state = ssi_param_state;
                break;
            }

            break;

        case ssi_param_state:
            switch (ch)
            {
            case ' ':
            case CR:
            case LF:
            case '\t': state = ssi_preequal_state; break;

            case '=': state = ssi_prevalue_state; break;

            case '-':
                state = ssi_error_end0_state;

                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "unexpected \"-\" symbol after \"%V\" "
                              "parameter in \"%V\" SSI command",
                              &ctx->param->key, &ctx->command);
                break;

            default:
                if (ctx->param->key.len == NGX_HTTP_SSI_PARAM_LEN)
                {
                    state = ssi_error_state;
                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                  "too long \"%V%c...\" parameter in "
                                  "\"%V\" SSI command",
                                  &ctx->param->key, ch, &ctx->command);
                    break;
                }

                ctx->param->key.data[ctx->param->key.len++] = ch;
            }

            break;

        case ssi_preequal_state:
            switch (ch)
            {
            case ' ':
            case CR:
            case LF:
            case '\t': break;

            case '=': state = ssi_prevalue_state; break;

            default:
                if (ch == '-')
                {
                    state = ssi_error_end0_state;
                }
                else
                {
                    state = ssi_error_state;
                }

                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "unexpected \"%c\" symbol after \"%V\" "
                              "parameter in \"%V\" SSI command",
                              ch, &ctx->param->key, &ctx->command);
                break;
            }

            break;

        case ssi_prevalue_state:
            switch (ch)
            {
            case ' ':
            case CR:
            case LF:
            case '\t': break;

            case '"': state = ssi_double_quoted_value_state; break;

            case '\'': state = ssi_quoted_value_state; break;

            default:
                if (ch == '-')
                {
                    state = ssi_error_end0_state;
                }
                else
                {
                    state = ssi_error_state;
                }

                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "unexpected \"%c\" symbol before value of "
                              "\"%V\" parameter in \"%V\" SSI command",
                              ch, &ctx->param->key, &ctx->command);
                break;
            }

            break;

        case ssi_double_quoted_value_state:
            switch (ch)
            {
            case '"': state = ssi_postparam_state; break;

            case '\\':
                ctx->saved_state = ssi_double_quoted_value_state;
                state            = ssi_quoted_symbol_state;

                /* fall through */

            default:
                if (ctx->param->value.len == ctx->value_len)
                {
                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                  "too long \"%V%c...\" value of \"%V\" "
                                  "parameter in \"%V\" SSI command",
                                  &ctx->param->value, ch, &ctx->param->key,
                                  &ctx->command);
                    state = ssi_error_state;
                    break;
                }

                ctx->param->value.data[ctx->param->value.len++] = ch;
            }

            break;

        case ssi_quoted_value_state:
            switch (ch)
            {
            case '\'': state = ssi_postparam_state; break;

            case '\\':
                ctx->saved_state = ssi_quoted_value_state;
                state            = ssi_quoted_symbol_state;

                /* fall through */

            default:
                if (ctx->param->value.len == ctx->value_len)
                {
                    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                                  "too long \"%V%c...\" value of \"%V\" "
                                  "parameter in \"%V\" SSI command",
                                  &ctx->param->value, ch, &ctx->param->key,
                                  &ctx->command);
                    state = ssi_error_state;
                    break;
                }

                ctx->param->value.data[ctx->param->value.len++] = ch;
            }

            break;

        case ssi_quoted_symbol_state:
            state = ctx->saved_state;

            if (ctx->param->value.len == ctx->value_len)
            {
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "too long \"%V%c...\" value of \"%V\" "
                              "parameter in \"%V\" SSI command",
                              &ctx->param->value, ch, &ctx->param->key,
                              &ctx->command);
                state = ssi_error_state;
                break;
            }

            ctx->param->value.data[ctx->param->value.len++] = ch;

            break;

        case ssi_postparam_state:

            if (ctx->param->value.len + 1 < ctx->value_len / 2)
            {
                value = ngx_pnalloc(r->pool, ctx->param->value.len + 1);
                if (value == NULL)
                {
                    return NGX_ERROR;
                }

                ngx_memcpy(value, ctx->param->value.data,
                           ctx->param->value.len);

                ctx->value_buf         = ctx->param->value.data;
                ctx->param->value.data = value;
            }
            else
            {
                ctx->value_buf = NULL;
            }

            switch (ch)
            {
            case ' ':
            case CR:
            case LF:
            case '\t': state = ssi_preparam_state; break;

            case '-': state = ssi_comment_end0_state; break;

            default:
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "unexpected \"%c\" symbol after \"%V\" value "
                              "of \"%V\" parameter in \"%V\" SSI command",
                              ch, &ctx->param->value, &ctx->param->key,
                              &ctx->command);
                state = ssi_error_state;
                break;
            }

            break;

        case ssi_comment_end0_state:
            switch (ch)
            {
            case '-': state = ssi_comment_end1_state; break;

            default:
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "unexpected \"%c\" symbol in \"%V\" SSI command",
                              ch, &ctx->command);
                state = ssi_error_state;
                break;
            }

            break;

        case ssi_comment_end1_state:
            switch (ch)
            {
            case '>':
                ctx->state    = ssi_start_state;
                ctx->pos      = p + 1;
                ctx->looked   = looked;
                ctx->copy_end = copy_end;

                if (ctx->copy_start == NULL && copy_end)
                {
                    ctx->copy_start = ctx->buf->pos;
                }

                return NGX_OK;

            default:
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "unexpected \"%c\" symbol in \"%V\" SSI command",
                              ch, &ctx->command);
                state = ssi_error_state;
                break;
            }

            break;

        case ssi_error_state:
            switch (ch)
            {
            case '-': state = ssi_error_end0_state; break;

            default: break;
            }

            break;

        case ssi_error_end0_state:
            switch (ch)
            {
            case '-': state = ssi_error_end1_state; break;

            default: state = ssi_error_state; break;
            }

            break;

        case ssi_error_end1_state:
            switch (ch)
            {
            case '>':
                ctx->state    = ssi_start_state;
                ctx->pos      = p + 1;
                ctx->looked   = looked;
                ctx->copy_end = copy_end;

                if (ctx->copy_start == NULL && copy_end)
                {
                    ctx->copy_start = ctx->buf->pos;
                }

                return NGX_HTTP_SSI_ERROR;

            default: state = ssi_error_state; break;
            }

            break;
        }
    }

    ctx->state  = state;
    ctx->pos    = p;
    ctx->looked = looked;

    ctx->copy_end = (state == ssi_start_state) ? p : copy_end;

    if (ctx->copy_start == NULL && ctx->copy_end)
    {
        ctx->copy_start = ctx->buf->pos;
    }

    return NGX_AGAIN;
}


static ngx_str_t *
ngx_http_ssi_get_variable(ngx_http_request_t *r, ngx_str_t *name,
                          ngx_uint_t key)
{
    ngx_uint_t          i;
    ngx_list_part_t    *part;
    ngx_http_ssi_var_t *var;
    ngx_http_ssi_ctx_t *ctx;

    ctx = ngx_http_get_module_ctx(r->main, ngx_http_ssi_filter_module);

#if (NGX_PCRE)
    {
        ngx_str_t *value;

        if (key >= '0' && key <= '9')
        {
            i = key - '0';

            if (i < ctx->ncaptures)
            {
                value = ngx_palloc(r->pool, sizeof(ngx_str_t));
                if (value == NULL)
                {
                    return NULL;
                }

                i *= 2;

                value->data = ctx->captures_data + ctx->captures[i];
                value->len  = ctx->captures[i + 1] - ctx->captures[i];

                return value;
            }
        }
    }
#endif

    if (ctx->variables == NULL)
    {
        return NULL;
    }

    part = &ctx->variables->part;
    var  = part->elts;

    for (i = 0; /* void */; i++)
    {
        if (i >= part->nelts)
        {
            if (part->next == NULL)
            {
                break;
            }

            part = part->next;
            var  = part->elts;
            i    = 0;
        }

        if (name->len != var[i].name.len)
        {
            continue;
        }

        if (key != var[i].key)
        {
            continue;
        }

        if (ngx_strncmp(name->data, var[i].name.data, name->len) == 0)
        {
            return &var[i].value;
        }
    }

    return NULL;
}


static ngx_int_t
ngx_http_ssi_evaluate_string(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                             ngx_str_t *text, ngx_uint_t flags)
{
    u_char                     ch, *p, **value, *data, *part_data;
    size_t                    *size, len, prefix, part_len;
    ngx_str_t                  var, *val;
    ngx_uint_t                 i, n, bracket, quoted, key;
    ngx_array_t                lengths, values;
    ngx_http_variable_value_t *vv;

    n = ngx_http_script_variables_count(text);

    if (n == 0)
    {
        data = text->data;
        p    = data;

        if ((flags & NGX_HTTP_SSI_ADD_PREFIX) && text->data[0] != '/')
        {
            for (prefix = r->uri.len; prefix; prefix--)
            {
                if (r->uri.data[prefix - 1] == '/')
                {
                    break;
                }
            }

            if (prefix)
            {
                len = prefix + text->len;

                data = ngx_pnalloc(r->pool, len);
                if (data == NULL)
                {
                    return NGX_ERROR;
                }

                p = ngx_copy(data, r->uri.data, prefix);
            }
        }

        quoted = 0;

        for (i = 0; i < text->len; i++)
        {
            ch = text->data[i];

            if (!quoted)
            {
                if (ch == '\\')
                {
                    quoted = 1;
                    continue;
                }
            }
            else
            {
                quoted = 0;

                if (ch != '\\' && ch != '\'' && ch != '"' && ch != '$')
                {
                    *p++ = '\\';
                }
            }

            *p++ = ch;
        }

        text->len  = p - data;
        text->data = data;

        return NGX_OK;
    }

    if (ngx_array_init(&lengths, r->pool, 8, sizeof(size_t *)) != NGX_OK)
    {
        return NGX_ERROR;
    }

    if (ngx_array_init(&values, r->pool, 8, sizeof(u_char *)) != NGX_OK)
    {
        return NGX_ERROR;
    }

    len = 0;
    i   = 0;

    while (i < text->len)
    {
        if (text->data[i] == '$')
        {
            var.len = 0;

            if (++i == text->len)
            {
                goto invalid_variable;
            }

            if (text->data[i] == '{')
            {
                bracket = 1;

                if (++i == text->len)
                {
                    goto invalid_variable;
                }

                var.data = &text->data[i];
            }
            else
            {
                bracket  = 0;
                var.data = &text->data[i];
            }

            for (/* void */; i < text->len; i++, var.len++)
            {
                ch = text->data[i];

                if (ch == '}' && bracket)
                {
                    i++;
                    bracket = 0;
                    break;
                }

                if ((ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z')
                    || (ch >= '0' && ch <= '9') || ch == '_')
                {
                    continue;
                }

                break;
            }

            if (bracket)
            {
                ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                              "the closing bracket in \"%V\" "
                              "variable is missing",
                              &var);
                return NGX_HTTP_SSI_ERROR;
            }

            if (var.len == 0)
            {
                goto invalid_variable;
            }

            key = ngx_hash_strlow(var.data, var.data, var.len);

            val = ngx_http_ssi_get_variable(r, &var, key);

            if (val == NULL)
            {
                vv = ngx_http_get_variable(r, &var, key);
                if (vv == NULL)
                {
                    return NGX_ERROR;
                }

                if (vv->not_found)
                {
                    continue;
                }

                part_data = vv->data;
                part_len  = vv->len;
            }
            else
            {
                part_data = val->data;
                part_len  = val->len;
            }
        }
        else
        {
            part_data = &text->data[i];
            quoted    = 0;

            for (p = part_data; i < text->len; i++)
            {
                ch = text->data[i];

                if (!quoted)
                {
                    if (ch == '\\')
                    {
                        quoted = 1;
                        continue;
                    }

                    if (ch == '$')
                    {
                        break;
                    }
                }
                else
                {
                    quoted = 0;

                    if (ch != '\\' && ch != '\'' && ch != '"' && ch != '$')
                    {
                        *p++ = '\\';
                    }
                }

                *p++ = ch;
            }

            part_len = p - part_data;
        }

        len += part_len;

        size = ngx_array_push(&lengths);
        if (size == NULL)
        {
            return NGX_ERROR;
        }

        *size = part_len;

        value = ngx_array_push(&values);
        if (value == NULL)
        {
            return NGX_ERROR;
        }

        *value = part_data;
    }

    prefix = 0;

    size  = lengths.elts;
    value = values.elts;

    if (flags & NGX_HTTP_SSI_ADD_PREFIX)
    {
        for (i = 0; i < values.nelts; i++)
        {
            if (size[i] != 0)
            {
                if (*value[i] != '/')
                {
                    for (prefix = r->uri.len; prefix; prefix--)
                    {
                        if (r->uri.data[prefix - 1] == '/')
                        {
                            len += prefix;
                            break;
                        }
                    }
                }

                break;
            }
        }
    }

    p = ngx_pnalloc(r->pool, len + ((flags & NGX_HTTP_SSI_ADD_ZERO) ? 1 : 0));
    if (p == NULL)
    {
        return NGX_ERROR;
    }

    text->len  = len;
    text->data = p;

    p = ngx_copy(p, r->uri.data, prefix);

    for (i = 0; i < values.nelts; i++)
    {
        p = ngx_copy(p, value[i], size[i]);
    }

    return NGX_OK;

invalid_variable:

    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                  "invalid variable name in \"%V\"", text);

    return NGX_HTTP_SSI_ERROR;
}


static ngx_int_t
ngx_http_ssi_regex_match(ngx_http_request_t *r, ngx_str_t *pattern,
                         ngx_str_t *str)
{
#if (NGX_PCRE)
    int                 rc, *captures;
    u_char             *p, errstr[NGX_MAX_CONF_ERRSTR];
    size_t              size;
    ngx_str_t          *vv, name, value;
    ngx_uint_t          i, n, key;
    ngx_http_ssi_ctx_t *ctx;
    ngx_http_ssi_var_t *var;
    ngx_regex_compile_t rgc;

    ngx_memzero(&rgc, sizeof(ngx_regex_compile_t));

    rgc.pattern  = *pattern;
    rgc.pool     = r->pool;
    rgc.err.len  = NGX_MAX_CONF_ERRSTR;
    rgc.err.data = errstr;

    if (ngx_regex_compile(&rgc) != NGX_OK)
    {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "%V", &rgc.err);
        return NGX_HTTP_SSI_ERROR;
    }

    n = (rgc.captures + 1) * 3;

    captures = ngx_palloc(r->pool, n * sizeof(int));
    if (captures == NULL)
    {
        return NGX_ERROR;
    }

    rc = ngx_regex_exec(rgc.regex, str, captures, n);

    if (rc < NGX_REGEX_NO_MATCHED)
    {
        ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                      ngx_regex_exec_n " failed: %d on \"%V\" using \"%V\"", rc,
                      str, pattern);
        return NGX_HTTP_SSI_ERROR;
    }

    if (rc == NGX_REGEX_NO_MATCHED)
    {
        return NGX_DECLINED;
    }

    ctx = ngx_http_get_module_ctx(r->main, ngx_http_ssi_filter_module);

    ctx->ncaptures     = rc;
    ctx->captures      = captures;
    ctx->captures_data = str->data;

    if (rgc.named_captures > 0)
    {
        if (ctx->variables == NULL)
        {
            ctx->variables =
                ngx_list_create(r->pool, 4, sizeof(ngx_http_ssi_var_t));
            if (ctx->variables == NULL)
            {
                return NGX_ERROR;
            }
        }

        size = rgc.name_size;
        p    = rgc.names;

        for (i = 0; i < (ngx_uint_t)rgc.named_captures; i++, p += size)
        {
            name.data = &p[2];
            name.len  = ngx_strlen(name.data);

            n = 2 * ((p[0] << 8) + p[1]);

            value.data = &str->data[captures[n]];
            value.len  = captures[n + 1] - captures[n];

            key = ngx_hash_strlow(name.data, name.data, name.len);

            vv = ngx_http_ssi_get_variable(r, &name, key);

            if (vv)
            {
                *vv = value;
                continue;
            }

            var = ngx_list_push(ctx->variables);
            if (var == NULL)
            {
                return NGX_ERROR;
            }

            var->name  = name;
            var->key   = key;
            var->value = value;
        }
    }

    return NGX_OK;

#else

    ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
                  "the using of the regex \"%V\" in SSI requires PCRE library",
                  pattern);
    return NGX_HTTP_SSI_ERROR;

#endif
}


static ngx_int_t
ngx_http_ssi_include(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                     ngx_str_t **params)
{
    ngx_int_t                   rc;
    ngx_str_t                  *uri, *file, *wait, *set, *stub, args;
    ngx_buf_t                  *b;
    ngx_uint_t                  flags, i, key;
    ngx_chain_t                *cl, *tl, **ll, *out;
    ngx_http_request_t         *sr;
    ngx_http_ssi_var_t         *var;
    ngx_http_ssi_ctx_t         *mctx;
    ngx_http_ssi_block_t       *bl;
    ngx_http_post_subrequest_t *psr;

    uri  = params[NGX_HTTP_SSI_INCLUDE_VIRTUAL];
    file = params[NGX_HTTP_SSI_INCLUDE_FILE];
    wait = params[NGX_HTTP_SSI_INCLUDE_WAIT];
    set  = params[NGX_HTTP_SSI_INCLUDE_SET];
    stub = params[NGX_HTTP_SSI_INCLUDE_STUB];

    if (uri && file)
    {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "inclusion may be either virtual=\"%V\" or file=\"%V\"",
                      uri, file);
        return NGX_HTTP_SSI_ERROR;
    }

    if (uri == NULL && file == NULL)
    {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "no parameter in \"include\" SSI command");
        return NGX_HTTP_SSI_ERROR;
    }

    if (set && stub)
    {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "\"set\" and \"stub\" cannot be used together "
                      "in \"include\" SSI command");
        return NGX_HTTP_SSI_ERROR;
    }

    if (wait)
    {
        if (uri == NULL)
        {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "\"wait\" cannot be used with file=\"%V\"", file);
            return NGX_HTTP_SSI_ERROR;
        }

        if (wait->len == 2
            && ngx_strncasecmp(wait->data, (u_char *)"no", 2) == 0)
        {
            wait = NULL;
        }
        else if (wait->len != 3
                 || ngx_strncasecmp(wait->data, (u_char *)"yes", 3) != 0)
        {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "invalid value \"%V\" in the \"wait\" parameter",
                          wait);
            return NGX_HTTP_SSI_ERROR;
        }
    }

    if (uri == NULL)
    {
        uri  = file;
        wait = (ngx_str_t *)-1;
    }

    rc = ngx_http_ssi_evaluate_string(r, ctx, uri, NGX_HTTP_SSI_ADD_PREFIX);

    if (rc != NGX_OK)
    {
        return rc;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "ssi include: \"%V\"", uri);

    ngx_str_null(&args);
    flags = NGX_HTTP_LOG_UNSAFE;

    if (ngx_http_parse_unsafe_uri(r, uri, &args, &flags) != NGX_OK)
    {
        return NGX_HTTP_SSI_ERROR;
    }

    psr = NULL;

    mctx = ngx_http_get_module_ctx(r->main, ngx_http_ssi_filter_module);

    if (stub)
    {
        if (mctx->blocks)
        {
            bl = mctx->blocks->elts;
            for (i = 0; i < mctx->blocks->nelts; i++)
            {
                if (stub->len == bl[i].name.len
                    && ngx_strncmp(stub->data, bl[i].name.data, stub->len) == 0)
                {
                    goto found;
                }
            }
        }

        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "\"stub\"=\"%V\" for \"include\" not found", stub);
        return NGX_HTTP_SSI_ERROR;

    found:

        psr = ngx_palloc(r->pool, sizeof(ngx_http_post_subrequest_t));
        if (psr == NULL)
        {
            return NGX_ERROR;
        }

        psr->handler = ngx_http_ssi_stub_output;

        if (bl[i].count++)
        {
            out = NULL;
            ll  = &out;

            for (tl = bl[i].bufs; tl; tl = tl->next)
            {
                if (ctx->free)
                {
                    cl        = ctx->free;
                    ctx->free = ctx->free->next;
                    b         = cl->buf;
                }
                else
                {
                    b = ngx_alloc_buf(r->pool);
                    if (b == NULL)
                    {
                        return NGX_ERROR;
                    }

                    cl = ngx_alloc_chain_link(r->pool);
                    if (cl == NULL)
                    {
                        return NGX_ERROR;
                    }

                    cl->buf = b;
                }

                ngx_memcpy(b, tl->buf, sizeof(ngx_buf_t));

                b->pos = b->start;

                *ll      = cl;
                cl->next = NULL;
                ll       = &cl->next;
            }

            psr->data = out;
        }
        else
        {
            psr->data = bl[i].bufs;
        }
    }

    if (wait)
    {
        flags |= NGX_HTTP_SUBREQUEST_WAITED;
    }

    if (set)
    {
        key = ngx_hash_strlow(set->data, set->data, set->len);

        psr = ngx_palloc(r->pool, sizeof(ngx_http_post_subrequest_t));
        if (psr == NULL)
        {
            return NGX_ERROR;
        }

        psr->handler = ngx_http_ssi_set_variable;
        psr->data    = ngx_http_ssi_get_variable(r, set, key);

        if (psr->data == NULL)
        {
            if (mctx->variables == NULL)
            {
                mctx->variables =
                    ngx_list_create(r->pool, 4, sizeof(ngx_http_ssi_var_t));
                if (mctx->variables == NULL)
                {
                    return NGX_ERROR;
                }
            }

            var = ngx_list_push(mctx->variables);
            if (var == NULL)
            {
                return NGX_ERROR;
            }

            var->name  = *set;
            var->key   = key;
            var->value = ngx_http_ssi_null_string;
            psr->data  = &var->value;
        }

        flags |= NGX_HTTP_SUBREQUEST_IN_MEMORY | NGX_HTTP_SUBREQUEST_WAITED;
    }

    if (ngx_http_subrequest(r, uri, &args, &sr, psr, flags) != NGX_OK)
    {
        return NGX_HTTP_SSI_ERROR;
    }

    if (wait == NULL && set == NULL)
    {
        return NGX_OK;
    }

    if (ctx->wait == NULL)
    {
        ctx->wait = sr;

        return NGX_AGAIN;
    }
    else
    {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "can only wait for one subrequest at a time");
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_stub_output(ngx_http_request_t *r, void *data, ngx_int_t rc)
{
    ngx_chain_t *out;

    if (rc == NGX_ERROR || r->connection->error || r->request_output)
    {
        return rc;
    }

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "ssi stub output: \"%V?%V\"", &r->uri, &r->args);

    out = data;

    if (!r->header_sent)
    {
        r->headers_out.content_type_len =
            r->parent->headers_out.content_type_len;
        r->headers_out.content_type = r->parent->headers_out.content_type;

        if (ngx_http_send_header(r) == NGX_ERROR)
        {
            return NGX_ERROR;
        }
    }

    return ngx_http_output_filter(r, out);
}


static ngx_int_t
ngx_http_ssi_set_variable(ngx_http_request_t *r, void *data, ngx_int_t rc)
{
    ngx_str_t *value = data;

    if (r->headers_out.status < NGX_HTTP_SPECIAL_RESPONSE && r->out
        && r->out->buf)
    {
        value->len  = r->out->buf->last - r->out->buf->pos;
        value->data = r->out->buf->pos;
    }

    return rc;
}


static ngx_int_t
ngx_http_ssi_echo(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                  ngx_str_t **params)
{
    u_char                    *p;
    uintptr_t                  len;
    ngx_buf_t                 *b;
    ngx_str_t                 *var, *value, *enc, text;
    ngx_uint_t                 key;
    ngx_chain_t               *cl;
    ngx_http_variable_value_t *vv;

    var = params[NGX_HTTP_SSI_ECHO_VAR];

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "ssi echo \"%V\"",
                   var);

    key = ngx_hash_strlow(var->data, var->data, var->len);

    value = ngx_http_ssi_get_variable(r, var, key);

    if (value == NULL)
    {
        vv = ngx_http_get_variable(r, var, key);

        if (vv == NULL)
        {
            return NGX_HTTP_SSI_ERROR;
        }

        if (!vv->not_found)
        {
            text.data = vv->data;
            text.len  = vv->len;
            value     = &text;
        }
    }

    if (value == NULL)
    {
        value = params[NGX_HTTP_SSI_ECHO_DEFAULT];

        if (value == NULL)
        {
            value = &ngx_http_ssi_none;
        }
        else if (value->len == 0)
        {
            return NGX_OK;
        }
    }
    else
    {
        if (value->len == 0)
        {
            return NGX_OK;
        }
    }

    enc = params[NGX_HTTP_SSI_ECHO_ENCODING];

    if (enc)
    {
        if (enc->len == 4 && ngx_strncmp(enc->data, "none", 4) == 0)
        {
            ctx->encoding = NGX_HTTP_SSI_NO_ENCODING;
        }
        else if (enc->len == 3 && ngx_strncmp(enc->data, "url", 3) == 0)
        {
            ctx->encoding = NGX_HTTP_SSI_URL_ENCODING;
        }
        else if (enc->len == 6 && ngx_strncmp(enc->data, "entity", 6) == 0)
        {
            ctx->encoding = NGX_HTTP_SSI_ENTITY_ENCODING;
        }
        else
        {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "unknown encoding \"%V\" in the \"echo\" command",
                          enc);
        }
    }

    p = value->data;

    switch (ctx->encoding)
    {
    case NGX_HTTP_SSI_URL_ENCODING:
        len =
            2 * ngx_escape_uri(NULL, value->data, value->len, NGX_ESCAPE_HTML);

        if (len)
        {
            p = ngx_pnalloc(r->pool, value->len + len);
            if (p == NULL)
            {
                return NGX_HTTP_SSI_ERROR;
            }

            (void)ngx_escape_uri(p, value->data, value->len, NGX_ESCAPE_HTML);
        }

        len += value->len;
        break;

    case NGX_HTTP_SSI_ENTITY_ENCODING:
        len = ngx_escape_html(NULL, value->data, value->len);

        if (len)
        {
            p = ngx_pnalloc(r->pool, value->len + len);
            if (p == NULL)
            {
                return NGX_HTTP_SSI_ERROR;
            }

            (void)ngx_escape_html(p, value->data, value->len);
        }

        len += value->len;
        break;

    default: /* NGX_HTTP_SSI_NO_ENCODING */ len = value->len; break;
    }

    b = ngx_calloc_buf(r->pool);
    if (b == NULL)
    {
        return NGX_HTTP_SSI_ERROR;
    }

    cl = ngx_alloc_chain_link(r->pool);
    if (cl == NULL)
    {
        return NGX_HTTP_SSI_ERROR;
    }

    b->memory = 1;
    b->pos    = p;
    b->last   = p + len;

    cl->buf        = b;
    cl->next       = NULL;
    *ctx->last_out = cl;
    ctx->last_out  = &cl->next;

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_config(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                    ngx_str_t **params)
{
    ngx_str_t *value;

    value = params[NGX_HTTP_SSI_CONFIG_TIMEFMT];

    if (value)
    {
        ctx->timefmt.len  = value->len;
        ctx->timefmt.data = ngx_pnalloc(r->pool, value->len + 1);
        if (ctx->timefmt.data == NULL)
        {
            return NGX_ERROR;
        }

        ngx_cpystrn(ctx->timefmt.data, value->data, value->len + 1);
    }

    value = params[NGX_HTTP_SSI_CONFIG_ERRMSG];

    if (value)
    {
        ctx->errmsg = *value;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_set(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                 ngx_str_t **params)
{
    ngx_int_t           rc;
    ngx_str_t          *name, *value, *vv;
    ngx_uint_t          key;
    ngx_http_ssi_var_t *var;
    ngx_http_ssi_ctx_t *mctx;

    mctx = ngx_http_get_module_ctx(r->main, ngx_http_ssi_filter_module);

    if (mctx->variables == NULL)
    {
        mctx->variables =
            ngx_list_create(r->pool, 4, sizeof(ngx_http_ssi_var_t));
        if (mctx->variables == NULL)
        {
            return NGX_ERROR;
        }
    }

    name  = params[NGX_HTTP_SSI_SET_VAR];
    value = params[NGX_HTTP_SSI_SET_VALUE];

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "ssi set \"%V\" \"%V\"", name, value);

    rc = ngx_http_ssi_evaluate_string(r, ctx, value, 0);

    if (rc != NGX_OK)
    {
        return rc;
    }

    key = ngx_hash_strlow(name->data, name->data, name->len);

    vv = ngx_http_ssi_get_variable(r, name, key);

    if (vv)
    {
        *vv = *value;
        return NGX_OK;
    }

    var = ngx_list_push(mctx->variables);
    if (var == NULL)
    {
        return NGX_ERROR;
    }

    var->name  = *name;
    var->key   = key;
    var->value = *value;

    ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "set: \"%V\"=\"%V\"", name, value);

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_if(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                ngx_str_t **params)
{
    u_char    *p, *last;
    ngx_str_t *expr, left, right;
    ngx_int_t  rc;
    ngx_uint_t negative, noregex, flags;

    if (ctx->command.len == 2)
    {
        if (ctx->conditional)
        {
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "the \"if\" command inside the \"if\" command");
            return NGX_HTTP_SSI_ERROR;
        }
    }

    if (ctx->output_chosen)
    {
        ctx->output = 0;
        return NGX_OK;
    }

    expr = params[NGX_HTTP_SSI_IF_EXPR];

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "ssi if expr=\"%V\"", expr);

    left.data = expr->data;
    last      = expr->data + expr->len;

    for (p = left.data; p < last; p++)
    {
        if (*p >= 'A' && *p <= 'Z')
        {
            *p |= 0x20;
            continue;
        }

        if ((*p >= 'a' && *p <= 'z') || (*p >= '0' && *p <= '9') || *p == '$'
            || *p == '{' || *p == '}' || *p == '_' || *p == '"' || *p == '\'')
        {
            continue;
        }

        break;
    }

    left.len = p - left.data;

    while (p < last && *p == ' ')
    {
        p++;
    }

    flags = 0;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "left: \"%V\"",
                   &left);

    rc = ngx_http_ssi_evaluate_string(r, ctx, &left, flags);

    if (rc != NGX_OK)
    {
        return rc;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "evaluated left: \"%V\"", &left);

    if (p == last)
    {
        if (left.len)
        {
            ctx->output        = 1;
            ctx->output_chosen = 1;
        }
        else
        {
            ctx->output = 0;
        }

        ctx->conditional = NGX_HTTP_SSI_COND_IF;

        return NGX_OK;
    }

    if (p < last && *p == '=')
    {
        negative = 0;
        p++;
    }
    else if (p + 1 < last && *p == '!' && *(p + 1) == '=')
    {
        negative = 1;
        p += 2;
    }
    else
    {
        goto invalid_expression;
    }

    while (p < last && *p == ' ')
    {
        p++;
    }

    if (p < last - 1 && *p == '/')
    {
        if (*(last - 1) != '/')
        {
            goto invalid_expression;
        }

        noregex = 0;
        flags   = NGX_HTTP_SSI_ADD_ZERO;
        last--;
        p++;
    }
    else
    {
        noregex = 1;
        flags   = 0;

        if (p < last - 1 && p[0] == '\\' && p[1] == '/')
        {
            p++;
        }
    }

    right.len  = last - p;
    right.data = p;

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "right: \"%V\"",
                   &right);

    rc = ngx_http_ssi_evaluate_string(r, ctx, &right, flags);

    if (rc != NGX_OK)
    {
        return rc;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "evaluated right: \"%V\"", &right);

    if (noregex)
    {
        if (left.len != right.len)
        {
            rc = -1;
        }
        else
        {
            rc = ngx_strncmp(left.data, right.data, right.len);
        }
    }
    else
    {
        right.data[right.len] = '\0';

        rc = ngx_http_ssi_regex_match(r, &right, &left);

        if (rc == NGX_OK)
        {
            rc = 0;
        }
        else if (rc == NGX_DECLINED)
        {
            rc = -1;
        }
        else
        {
            return rc;
        }
    }

    if ((rc == 0 && !negative) || (rc != 0 && negative))
    {
        ctx->output        = 1;
        ctx->output_chosen = 1;
    }
    else
    {
        ctx->output = 0;
    }

    ctx->conditional = NGX_HTTP_SSI_COND_IF;

    return NGX_OK;

invalid_expression:

    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                  "invalid expression in \"%V\"", expr);

    return NGX_HTTP_SSI_ERROR;
}


static ngx_int_t
ngx_http_ssi_else(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                  ngx_str_t **params)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "ssi else");

    if (ctx->output_chosen)
    {
        ctx->output = 0;
    }
    else
    {
        ctx->output = 1;
    }

    ctx->conditional = NGX_HTTP_SSI_COND_ELSE;

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_endif(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                   ngx_str_t **params)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "ssi endif");

    ctx->output        = 1;
    ctx->output_chosen = 0;
    ctx->conditional   = 0;

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_block(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                   ngx_str_t **params)
{
    ngx_http_ssi_ctx_t   *mctx;
    ngx_http_ssi_block_t *bl;

    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "ssi block");

    mctx = ngx_http_get_module_ctx(r->main, ngx_http_ssi_filter_module);

    if (mctx->blocks == NULL)
    {
        mctx->blocks =
            ngx_array_create(r->pool, 4, sizeof(ngx_http_ssi_block_t));
        if (mctx->blocks == NULL)
        {
            return NGX_HTTP_SSI_ERROR;
        }
    }

    bl = ngx_array_push(mctx->blocks);
    if (bl == NULL)
    {
        return NGX_HTTP_SSI_ERROR;
    }

    bl->name  = *params[NGX_HTTP_SSI_BLOCK_NAME];
    bl->bufs  = NULL;
    bl->count = 0;

    ctx->output = 0;
    ctx->block  = 1;

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_endblock(ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx,
                      ngx_str_t **params)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "ssi endblock");

    ctx->output = 1;
    ctx->block  = 0;

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_date_gmt_local_variable(ngx_http_request_t        *r,
                                     ngx_http_variable_value_t *v,
                                     uintptr_t                  gmt)
{
    time_t              now;
    ngx_http_ssi_ctx_t *ctx;
    ngx_str_t          *timefmt;
    struct tm           tm;
    char                buf[NGX_HTTP_SSI_DATE_LEN];

    v->valid        = 1;
    v->no_cacheable = 0;
    v->not_found    = 0;

    now = ngx_time();

    ctx = ngx_http_get_module_ctx(r, ngx_http_ssi_filter_module);

    timefmt = ctx ? &ctx->timefmt : &ngx_http_ssi_timefmt;

    if (timefmt->len == sizeof("%s") - 1 && timefmt->data[0] == '%'
        && timefmt->data[1] == 's')
    {
        v->data = ngx_pnalloc(r->pool, NGX_TIME_T_LEN);
        if (v->data == NULL)
        {
            return NGX_ERROR;
        }

        v->len = ngx_sprintf(v->data, "%T", now) - v->data;

        return NGX_OK;
    }

    if (gmt)
    {
        ngx_libc_gmtime(now, &tm);
    }
    else
    {
        ngx_libc_localtime(now, &tm);
    }

    v->len = strftime(buf, NGX_HTTP_SSI_DATE_LEN, (char *)timefmt->data, &tm);
    if (v->len == 0)
    {
        return NGX_ERROR;
    }

    v->data = ngx_pnalloc(r->pool, v->len);
    if (v->data == NULL)
    {
        return NGX_ERROR;
    }

    ngx_memcpy(v->data, buf, v->len);

    return NGX_OK;
}


static ngx_int_t
ngx_http_ssi_preconfiguration(ngx_conf_t *cf)
{
    ngx_int_t                 rc;
    ngx_http_variable_t      *var, *v;
    ngx_http_ssi_command_t   *cmd;
    ngx_http_ssi_main_conf_t *smcf;

    for (v = ngx_http_ssi_vars; v->name.len; v++)
    {
        var = ngx_http_add_variable(cf, &v->name, v->flags);
        if (var == NULL)
        {
            return NGX_ERROR;
        }

        var->get_handler = v->get_handler;
        var->data        = v->data;
    }

    smcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_ssi_filter_module);

    for (cmd = ngx_http_ssi_commands; cmd->name.len; cmd++)
    {
        rc = ngx_hash_add_key(&smcf->commands, &cmd->name, cmd,
                              NGX_HASH_READONLY_KEY);

        if (rc == NGX_OK)
        {
            continue;
        }

        if (rc == NGX_BUSY)
        {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "conflicting SSI command \"%V\"", &cmd->name);
        }

        return NGX_ERROR;
    }

    return NGX_OK;
}


static void *
ngx_http_ssi_create_main_conf(ngx_conf_t *cf)
{
    ngx_http_ssi_main_conf_t *smcf;

    smcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_ssi_main_conf_t));
    if (smcf == NULL)
    {
        return NULL;
    }

    smcf->commands.pool      = cf->pool;
    smcf->commands.temp_pool = cf->temp_pool;

    if (ngx_hash_keys_array_init(&smcf->commands, NGX_HASH_SMALL) != NGX_OK)
    {
        return NULL;
    }

    return smcf;
}


static char *
ngx_http_ssi_init_main_conf(ngx_conf_t *cf, void *conf)
{
    ngx_http_ssi_main_conf_t *smcf = conf;

    ngx_hash_init_t hash;

    hash.hash        = &smcf->hash;
    hash.key         = ngx_hash_key;
    hash.max_size    = 1024;
    hash.bucket_size = ngx_cacheline_size;
    hash.name        = "ssi_command_hash";
    hash.pool        = cf->pool;
    hash.temp_pool   = NULL;

    if (ngx_hash_init(&hash, smcf->commands.keys.elts,
                      smcf->commands.keys.nelts)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}


static void *
ngx_http_ssi_create_loc_conf(ngx_conf_t *cf)
{
    ngx_http_ssi_loc_conf_t *slcf;

    slcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_ssi_loc_conf_t));
    if (slcf == NULL)
    {
        return NULL;
    }

    /*
     * set by ngx_pcalloc():
     *
     *     conf->types = { NULL };
     *     conf->types_keys = NULL;
     */

    slcf->enable                  = NGX_CONF_UNSET;
    slcf->silent_errors           = NGX_CONF_UNSET;
    slcf->ignore_recycled_buffers = NGX_CONF_UNSET;
    slcf->last_modified           = NGX_CONF_UNSET;

    slcf->min_file_chunk = NGX_CONF_UNSET_SIZE;
    slcf->value_len      = NGX_CONF_UNSET_SIZE;

    return slcf;
}


static char *
ngx_http_ssi_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_ssi_loc_conf_t *prev = parent;
    ngx_http_ssi_loc_conf_t *conf = child;

    ngx_conf_merge_value(conf->enable, prev->enable, 0);
    ngx_conf_merge_value(conf->silent_errors, prev->silent_errors, 0);
    ngx_conf_merge_value(conf->ignore_recycled_buffers,
                         prev->ignore_recycled_buffers, 0);
    ngx_conf_merge_value(conf->last_modified, prev->last_modified, 0);

    ngx_conf_merge_size_value(conf->min_file_chunk, prev->min_file_chunk, 1024);
    ngx_conf_merge_size_value(conf->value_len, prev->value_len, 255);

    if (ngx_http_merge_types(cf, &conf->types_keys, &conf->types,
                             &prev->types_keys, &prev->types,
                             ngx_http_html_default_types)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_ssi_filter_init(ngx_conf_t *cf)
{
    ngx_http_next_header_filter = ngx_http_top_header_filter;
    ngx_http_top_header_filter  = ngx_http_ssi_header_filter;

    ngx_http_next_body_filter = ngx_http_top_body_filter;
    ngx_http_top_body_filter  = ngx_http_ssi_body_filter;

    return NGX_OK;
}
